Optimum performance of a bow requires accurate calibration of the various bow components. For example, to ensure bow accuracy, the center shot of a bow is most often calibrated by aligning an arrow placed on an arrow rest in a straight line with the bow string, from where the nock pointing is set. When properly aligned, a center shot allows the energy stored in the limbs of the bow to be transferred down the core of the full length of the arrow shaft, thereby resulting in straight flight. Many methods and tools have been created for centering an arrow to a bow, but all have certain disadvantages.
A common and well-known trial-and-error method for centering an arrow to a bow involves shooting one un-fletched arrow, and two or more fletched arrows from the bow, and then observing the difference in orientation of the shot arrows in the archery target. The archer then adjusts the position of the arrow rest accordingly, and repeats the process until the arrows group in the target with the same vertical orientation—a time-consuming and error-prone process.
Another method for centering an arrow to the bow string consists of hanging a bow upside down with the string facing upwards, nocking an arrow on the string, allowing gravity to pull the arrow towards the ground, and then aligning the arrow rest with the position of the downward-facing arrow. Once the arrow rest is adjusted in this manner, the arrow is fired to test accuracy, and the process is also repeated until the archer is satisfied with the grouping of the arrows. This method may not only be time-consuming but also depends on the ability of the archer to manually hold the bow still.
A third potentially inaccurate method for centering an arrow to a bow consists of making two marks in the bow, one in the center of the top limb, and another in the center of the bottom limb. The string is then lined up to the top and bottom line, while at the same time moving the bow rest in or out from the riser until the arrow is aligned with the middle of string.
Similar to the aforementioned methods, some prior art arrow-centering tools may require a substantial amount of time to calibrate accurately, may be expensive to manufacture, and may not be conveniently portable, to name just a few disadvantages. For example, some arrow centering tools utilizing comparatively sophisticated (and relatively expensive) laser technology usually require that a laser be attached to the sight hole on the back side of the riser, require a power source, and may not be designed for optimal use in harsh environments. Some disadvantages of prior art arrow-centering tools are also highlighted by some currently-typical features of modern compound bows.
Thus, there exists a need for a tool for calibrating center shot that is conveniently portable, easy to use, and that allows an arrow to be centered in a relatively expeditious manner.